1. Field of the Invention
The present invention relates to an image forming apparatus useful for a printing device of an electro-photographic system.
2. Description of Related Art
In the printing device of the electro-photographic system, the following control has been employed for fusing the transferred toner on a print medium. First of all, a fuser is pre-heated up to such a temperature that the toner is sufficiently fused by the fuser. The fuser is pre-heated by applying electric power to an exothermic device contained therein. Then, the print medium carrying a toner image is subject to the fuser. The fuser keeps the temperature from a time when the front end of the print medium reaches the fuser till a time when the rear end of the print medium passes through the fuser. During the period of time, the print medium is heated by the fuser so that the toner image is fused. After the fusing, the application of electric power is stopped to cool the fuser.
However, in such a conventional printing device, the fuser keeps the predetermined temperature until the entire print medium passes through it. Accordingly, even if the print medium includes only a toner image, the fuser is heated until the medium passes through it. Consequently, electric power is wasted and the exothermic device is degraded earlier.
Accordingly, it is an object of the invention to provide an image forming apparatus capable of reducing the power consumption and preventing early degradation of the exothermic device.
According to the invention, there is provided an image forming apparatus comprising an image forming unit for forming a toner image onto a print medium, a fusing unit for fusing the toner image formed on the print medium and feeding the print medium, a heat generating unit for heating the fusing unit, a power supplying unit for supplying electric power to the heat generating unit, and a print controlling unit for executing printing process in accordance with an input printing information and controlling the supply of electric power to the heat generating unit. The print controlling unit detects an end of the printing information and stops the supply of electric power to the heat generating means in response to the detection of the end of the printing information.